package com.lysh.test.io;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

/**
 * @author liyishan
 * @date 2023/5/5 14:59
 * @apiNote   NIO多路复用器
 */

public class ScoketServerChannle2 {
    public static void main(String[] args) throws IOException {
        //创建NIO ServerSocketChannel 与BIO的serverSocket类似
        ServerSocketChannel serverSocket = ServerSocketChannel.open();
        serverSocket.socket().bind(new InetSocketAddress(9000));
        //设置ServerSocketChannel为非阻塞
        serverSocket.configureBlocking(false);
        //多路复用器
        Selector selector = Selector.open();
        //把ServerSocketChannel注册到Selector上，且selector对客户端accept连接操作的关注
        SelectionKey selectionKey = serverSocket.register(selector,SelectionKey.OP_ACCEPT);
        System.out.println("服务启动成功");

        while(true){
            //阻塞等待需要处理的事件发生
            selector.select();
            //获取selector中注册的全部事件的SelectionKey实例
            Set<SelectionKey> selectionKeys = selector.selectedKeys();
            Iterator<SelectionKey> iterator = selectionKeys.iterator();
            //遍历SelectionKey对事件进行处理   高并发下不能遍历
            while(iterator.hasNext()){
                SelectionKey key = iterator.next();
                //如果是OP_ACCEPT事件，则进行连接获取和事件注册
                if(key.isAcceptable()){
                    ServerSocketChannel server = (ServerSocketChannel)key.channel();
                    SocketChannel socketChannel = server.accept();
                    socketChannel.configureBlocking(false);
                    //这里之注册了读事件，如果需要给客户端发送数据可以注册写事件
                    SelectionKey selKey = socketChannel.register(selector,SelectionKey.OP_READ);
                    System.out.println("客户端连接成功");
                }else if(key.isReadable()){  //如果是OP_READ事件，则进行读取和打印
                    SocketChannel socketChannel = (SocketChannel)key.channel();
                    ByteBuffer byteBuffer = ByteBuffer.allocate(128);
                    int len = socketChannel.read(byteBuffer);
                    //如果由数据，把数据打印出来
                    if(len>0){
                        System.out.println("接收到消息："+new String(byteBuffer.array()));
                    }else if(len == -1){   //如果客户端断开连接，关闭Socket
                        System.out.println("客户端断开连接");
                        socketChannel.close();
                    }
                }
                //从事件集合里删除本次处理的key，防止下次select重复处理
                iterator.remove();
            }
        }
    }
}
